Linear polyesters from p, p&#39;-sulfonyl dibenzoic acid plus aliphatic dibasic ether acids condensed with a glycol



inclusive, the dioxy compound being employed in such a proportion that there is at least an equivalent amount of oxy substituents in proportion to the carbalkoxy substituents in the overall combination of the diesters and the dioxy compounds, (C) in the presence of a condensing agent selected from the group consisting of the alkali metals, the alkaline earth metals, the oxides of these two groups of metals, the alkoxides containing from 1 to 6 carbon atoms of these two groups of metals, the carbonates and borates of these groups of metals, lead oxide, and compounds having the following formulas:

wherein M represents an alkali metal, M represents an alkaline earth metal selected from the group consisting of magnesium, calcium and strontium, R represents an alkyl group containing from 1 to 6 carbon atoms, R, R" and R'" each represents a member of the group consisting of R and an aryl group of the benzene series containing from 6 to 9 carbon atoms and Hal represents a halogen atom, (D) at an elevated temperature, (E) the condensation being conducted in an inert atmosphere, and (F) the latter part of the condensation being conducted at a very low pressure of the inert atmosphere.

Advantageously, the dioxy compound is employed in such a proportion that there are from about 1.2 to about 3 oxy substituents in proportion to the carbalkoxy substituents in the overall combination of the diesters and the dioxy compounds. Advantageously, the low pressure defined under (F) is less than about mm. of Hg pressure. Advantageously, the elevated temperature employed during the earlier part of the condensation is from about 150 to about 220 C. Advantageously, the dioxy compound is a glycol having the formula:

wherein p is defined under (B) above.

The dioxy compounds defined above may not actually contain any free hydroxy radicals since they may be in esterified form as indicated by the formulas given. However, these hydroxy or substituted hydroxy radicals are referred to generically as oxy radicals or substituents. The dioxy compounds which can be employed in accordance with this invention are most advantageously dihydroxy compounds; such compounds will hereinafter be referred to as dihydroxy compounds although it is to be understood that dioxy compounds of the type described above are intended to be covered by this term. Each diester is considered as containing two carbalkoxy radicals as that term is employed in the definition of the process as described above since R1 and R4 may be alkyl radicals, omega hydroxyalkyl radicals, or B-hydroxyalkyl radicals and Re and R9 may be alkyl radicals or omega hydroxyalkyl radicals. Even when the process is preceded by the preliminary step described below employing free acids, the term carbalkoxy radicals in the description of the process is intended to encompass such free carboxy radicals.

Furthermore, this invention covers a process as defined above wherein either or both of the sulfonyl dibenzoic acid diester and the aliphatic acid diester is/ are formed by a preliminary step comprising condensing free p,psulfonyl dibenzoic and/or free aliphatic acid with a dihydroxy compound which is defined under (B) and is employed in the proportions set forth under (B), at an elevated temperature, after which preliminary step the condensing agent which is defined under (C) is added and the condensation is completed as defined under (D),

(E) and (F). Advantageously the elevated temperature employed during the preliminary step is substantially that at which reflux conditions subsist; however, higher and lower temperatures can also be employed. Advantageously, as indicated above the dihydroxy compound is employed in such a proportion that there are from about 1.2 to about 3 hydroxy substituents in proportion to the carboxy and carbalkoxy substituents in the overall combination of the diacids, diesters, and dihydroxy compounds.

As indicated above, the interpolyesters described herein have relatively wide softening ranges and good flow properties. In this respect, they differ from most types of high-melting linear polyesters, such as polyethylene terephthalate, which possess sharp melting points. Thus, these modified polyesters of sulfonyl dibenzoic acid soften over a sufliciently wide temperature range that they can be advantageously employed in the production of shaped objects by injection molding and extrusion methods.

The alkylene glycols which can be employed to form highly polymeric linear polyesters are straight-chain alkane diols, viz. polymethylene glycols, wherein the hydroxy radicals are positioned at the two ends of the alkylene chain. Examples of such glycols include ethylene glycol, 1,3-propylene glycol, 1,4-butylene glycol, 1,6- hexylcne glycol, 1,10-decamethylene glycol, 1,12-dodecamethylene glycol, etc. As indicated above, mono or diesters of these glycols can also be employed. Thus, the acetates, propionates and butyrates are examples of such esters. The defined ether glycols can be employed either in lieu of the polymethylene glycols or in conjunction therewith as modifiers. Mixtures of alkylene glycols or ether glycols can also be employed. Examples of ether glycols include diethylene glycol, triethylene glycol, tetraethylene glycol, bis (4-hydroxybutyl) ether, bis (3- hydroxypropyl) ether, etc. When mixtures of alkylene glycols and ether glycols are employed, it is generally preferable to employ a major proportion of the alkylene glycol in order to obtain higher melting linear polyesters. The high melting characteristic also is dependent upon the amount of aliphatic dibasic ether acid present in the interpolyester, the chain length of this aliphatic acid and the chain length of the glycol employed. Higher proportions of the aliphatic acid lower the melting and softening temperatures of the interpolyesters. This effect is also produced when a longer chain-length aliphatic acid is employed in the same proportions as a shorter chain length aliphatic acid. The same effect is created by employing a longer chain (higher carbon content) alkylene glycol. For example, when a 10-12 carbon atom glycol is employed, the amount of aliphatic ether glycol used should preferably be not more than about 10-20 mole per cent; whereas, when a 2-4 carbon atom glycol is employed the amount of ether glycol can be as high as about 50 mole per cent of the total quantity of dihydroxy compounds employed. When no ether glycol is employed, it is preferred to employ polymethylene glycols containing from 4 to 8 carbon atoms; this is especially important when the aliphatic acid has a rather short chain length, the proportion thereof is relatively low and the polymethylene glycol also has a short chain length (e. g. ethylene and trimethylene glycol) under which conditions the mole ratio of the p,p-sulfonyl dibenzoic ester to the aliphatic diester should be from 10:10 to 10:30 since the melting point of the interpolyester produced might otherwise be above 300 C. whereby decomposition would take place whenever the polyester was melted or softened.

Valuable fibers having high melting temperatures can be prepared by incorporating very little, preferably none, of an aliphatic ether glycol and less than 15 mole percent of the aliphatic dibasic acid (of the type described above) into an interpolyester containing about -90 mole percent of the p,p'-sulfonyl dibenzoic constituent. It is particularly advantageous to employ a polymethylene glycol to each 1 to about 30 of one of the following repeating units:

wherein s, t, and p are defined above.

When the ratio of the repeating units is, respectively, from about 10:1 to about 10: 2 these interpolyesters are capable of being spun into fibers which can be drawn to from about 3 to 6 times their originally spun length thereby developing strong, elastic properties distinguished by a high degree of reversible extensibility.

The above described interpolyesters can also have either one or both of the two types of repeating units depicted above replaced entirely or in part, respectively, by one of the following repeating units:

wherein s, t, q and R1 are defined above.

In the examples given below, the hot bar sticking temperature is referred to in several instances. The hot bar sticking test can be briefly described as follows: A polyester fiber is placed on the flat surface of a heated bar and a weight of 100 grams is applied to the fiber along a distance of inch of the fiber length. The contact surface of this weight has a coating of polytetrafiuoroethylene which acts as a. thermal insulator. The fiber is allowed to remain in contact with the bar under this weight for one minute. The minimum temperature at which the fiber adheres to the hot bar under these conditions is the sticking temperature as that term is employed in the examples given herein.

This invention can be further illustrated by the following examples; in addition to these examples it is apparent that other variations and modifications thereof can be adapted to obtain similar results:

Example 1.Diglycollic acid and tetramethylene glycol Two hundred and twenty-two grams (1.4 mole) of diglycollie acid monohydrate and 450 g. (5 moles) of tetramethylene glycol were placed in a reaction vessel equipped with a stirrer, a short distillation column, and an inlet for purified hydrogen. The mixture was stirred at 200- 210 for 1%-2 hours to convert the acid to the glycol ester. Four hundred and twenty grams (1.0 mole) of p,p'-sulfonyl dibenzo-ic acid dibutyl ester was then added to the reaction vessel. A solution of 0.3 g. sodium titanium butoxide in 10 cc. butyl alcohol was added as the catalyst. The mixture was then stirred at ZOO-210 C. in a stream of purified hydrogen until the distillation of butyl alcohol had practically come to a stop, showing that the ester interchange was complete. The temperature was then raised to 260 C. and held for 30 minutes. A vacuum of 1.0 to 2.0 mm. of Hg pressure was then applied for 2 hours, while stirring was continued. A product having an inherent viscosity of 0.60 to 0.70 in a 60% phenol-40% tetrachlorethane solution was obtained. This interpolyester has a relatively wide softening range and can be injection molded at ISO-200 C. to give products having a high impact strength. It is soluble in hot tetrachlorethane, phenol, and -butyrolactone. It can be extruded to give rods, sheets, tubes, etc. It is also useful as an electrical insulating material.

Example 2.-Diglycollic acid and pentamethylene glycol Three hundred and seventy-two grams (1.0 mole) of p,p-sulfonyl dibenzoic acid diethyl ester, 47 g. (0.25 mole) diglycollic acid diethyl ester, and 500 g. (4.4 moles) pentamethylene glycol were placed in a reaction vessel equipped with a stirrer, a short distillation column, and an inlet for purified nitrogen. A solution of 0.2 g. sodium aluminum ethoxide in ethanol was added as the catalyst.

The mixture was stirred at ZOO-210 C. until the distillation of ethyl alcohol was essentially complete. The temperature was then raised to 250-260 C. and maintained for 30 minutes. A vacuum of 2 to 3 mm. of Hg pressure was then applied and stirring was continued for 3 hours. A product having an inherent viscosity of 0.7 to 0.8 in 60% phenol-40% tetrachlorethane was obtained. This interpolyester is useful as a molding plastic. It can be extruded at 200-220 C. to give sheets, rods, tubes, etc. It is useful as a photographic film base material.

Example 3.-'y-Oxydibutyric acid and ethylene glycol Three hundred and seventy-two grams (1.0 mole) of p,p-sulfonyl dibenzoic acid diethyl ester, 500 g. (2.0 moles) of 'y-oxydibutyric acid diethyl ester, and 400 g. of ethylene glycol were placed in a reaction vessel as described in Example 1. A piece of magnesium ribbon weighing about 0.2 g. and a solution of 0.2 g. lithium ethoxide in ethanol were added as catalysts. A heating schedule similar to that described in Example 1, but of more extended duration, was followed, using a final temperature of 270275 C. The product obtained is useful as a molding plastic. It can be extruded into sheets, rods, tubes, etc. It softens at 200-210" C.

Example 4.Diglycollz'c acid and hexamethylene glycol The procedure described in Example 2 was repeated exactly-except that 525 grams of hexamethylene glycol were employed instead of the pentamethylene glycol. The interpolyester obtained has properties similar to those produced in Example 2 except that extrusion can be performed at a slightly lower temperature.

Example 5.'y-Carb0xymeth0xybutyric acid and octamethylene glycol The procedure described in Example 1 was repeated employing 0.18 gram mole (49 grams) of the dibutyl ester of 'y-carboxymethylbutyric acid, 1.0 gram mole of the dibutyl ester of p,p-sulfonyl dibenzoic acid (420 grams), 3.5 gram moles of octamethylene glycol (511 grams) and 0.3 gram of sodium titanium butoxide in 10 cc. of butyl alcohol as the catalyst. The initial temperature employed was 180-200 C. and the final temperature was 235 250 C. The interpolyester obtained was of good quality but had a somewhat lower softening point. The product can be used advantageously as a molding plastic.

Example 6.-Diglycollic acid, pentamethylene glycol and diethylene glycol The procedure described in Example 2 was repeated exactly except that the 4.4 moles of pentamethylene glycol was cut in half and 2.2 gram moles (233 g.) of diethylene glycol was used to make a total of 4.4 moles of dihydroxy compound consisting of equimolar quantities of pentarnethylene glycol and diethylene glycol. The interpolyester obtained was of lower viscosity than that produced in Example 2 but it is also useful in preparing sheets, rods, tubes, etc.

Example 7.-Diglycollic acid and pentamethylene glycol The procedure described in Example 2 was repeated exactly except that a solution of 0.5 g. of potassium ethoxide in ethanol was employed as the catalyst (in lieu of the sodium aluminum ethoxide) and the final heating period was extended from 3 hours to 6 hours. The interpolyester obtained had a somewhat lower viscosity than the product obtained in Example 2 but it was also useful for the purposes named above. Similar results can be obtained using as the catalyst: K, Ca, LizCOs, NazBOa, PbO (litharge), etc. Such catalysts can also be employed in the processes described in the other examples given above after making suitable allowances for the differences in the reaction rates inherent in the change of the catalyst.

7 .9 What I claim is: v,l. .A process. for preparingialinear, polyester comprising (A) condensing about 10- mole. .preparations ,of 7a p,p .-sulfonyldibenzoic diester, havingv theuformula:

.. R10-0 o-Qsm-Oo 0.-o R4 nwhereinRr-and Ri-each represents asubstituent selected from the group consisting of a fi-hydroxyalkyl radical containing from 2 to 4 carbon atoms, an omega-hydroxyalkyl radical. containing. from :3. to l2v carbon,v atoms and an alkyl radical containingfrom l to 6 carbon atoms,

plus from about l to about "3O-moleproportions of an aliphatic diester. .having .thecfollowingiformula:

:-.wherein,s-.and I each represents a positive- -integerzof from 1 to 4, inclusive, and Rev and .R9 each represents a substituent selected from' the group consisting of an,

wherein p represents a positive integer of from 2 to 12, R5 and Rs each represents a substituent selected from the group consisting of a hydrogen atom and an acyl radical containing from 2 to 4 carbon atoms, R7 represents an alkylene radical containing from 2 to 4 carbon atoms and q represents a positive integer of from 1 to 10 inclusive, the dioxy compound being employed in such a proportion that there is at least an equivalent amount of oxy substituents in proportion to the carbalkoxy substituents in the overall combination of the diesters and the dioxy compound, (C) in the presence of a condensing agent selected from the group consisting of the alkali metals, the alkaline earth metals, the oxides of these two groups of metals, the alkoxides containing from 1 to 6 carbon atoms of these two groups of metals, the carbonates and borates of these two groups of metals and lead oxide, (D) at an elevated temperature, (E) the condensation being conducted in an inert atmosphere, and (F) the latter part of the condensation being conducted at a very low pressure of the inert atmosphere, said process encompassing the condensation of only those compounds referred to in (A) and (B) hereinabove.

2. A process as defined in claim 1 wherein the elevated temperature is increased gradually during the course of the condensation up to a temperature of from about 225 to about 310 C.

3. A process as defined in claim 2 wherein the condensing agent is employed in an amount of from about 0.005% to about 0.2% based on the weight of the diesters employed.

4. A process as defined in claim 3 wherein the dioxy compound is employed in such a proportion that there are from about 1.2 to about 3 oxy substituents in proportion to the carbalkoxy substituents in the overall combination of the diesters and the dioxy compounds.

5. A process as defined in claim 4 wherein the elevated temperature employed during the earlier part of the condensation is from about 150 to about 220 C. and the low pressure defined under (F) is less than about mm. of Hg pressure.

6. A process as defined in claim 5 wherein all materials employed in the process are substantially anhydrous.

7. A process as defined in claim 6 wherein the dioxy compound has the formula:

HO(CH2)vOH wherein p is defined under (B).

5'10 cc -a de laim 17, whereini healiph ti LdiQSterL .is the. arhydro y uty diest f ".di ycolli a,cidand .the .dihydroxy compound is tetramethylene 'sly o ,9. 1 A vprocess as ,defined, in claim 7, wherein ,the; aliphatic diesterjs ,diethyl ,diglycollate and thetflihydl'qliy rcompound, is pentamethyleneglycol.

10.,A processas defined, in claim 7. wherein ,;t he,aliphatic diester is 'diethyl .yroxydibutyrate and .thewldihyfdroxycompoundisethylene glycol.

ll. .'A' process as definedin claim 7 wherein the aliphatic diester is diethyl diglycollate and the.dihydroxy compound is hexamethylene glycol.

12. A process as definedzin claim 6 whereinzthwaliphatic diSier.=. is dibutyl 'y-carboxymethoxybutyrate and the dihydroxy compound is octame thylene glycol.

- 1;3.-"*A--process 'as definedin claim 1' wherein-the-sul- -fon'yl dibenzoic*diester" is formed bya-- preliminary step "comprising condensing p,-p-sulf0nyl -dibenzo icacid with a dioxy compound which is defined under- (-B), atan elevated temperature, after which preliminary step the condensing agent which is defined under (C) is added and the condensation is completed as defined under (D),

(E) and (F).

14. A process as defined in claim 13 wherein the preliminary elevated temperature is substantially that at which reflux conditions subsist, the subsequent condensation being conducted at a temperature which is gradually increased during the course of the condensation up to about 280-3l0 C., and the dioxy compound is employed in such a proportion that there are from about 1.2 to about 3 oxy substituents in proportion to the carboxy and carbalkoxy substituents in the overall combination of the diacids, diesters and dioxy compounds.

15. A process as defined in claim 1 wherein the aliphatic diester is formed by a preliminary step comprising condensing an aliphatic acid selected from the group having the following formula:

wherein s and t each represents a positive integer of from 1 to 4 with a dioxy compound which is defined under (B), at an elevated temperature, after which preliminary step the condensing agent which is defined under (C) is added and the condensation is completed as defined under (D), (E) and (F).

16. A process as defined in claim 15 wherein the preliminary elevated temperature is substantially that at which reflux conditions subsist, the subsequent condensation being conducted at a temperature which is gradually increased during the course of the condensation up to about 280310 C., and the dioxy compound is employed in such a proportion that there are from about 1.2 to about 3 oxy substituents in proportion to the carboxy and carbalkoxy substituents in the overall combination of the diacids, diesters and dioxy compounds.

17. A process as defined in claim 16 wherein the condensing agent is employed in an amount of from about 0.005% to about 0.2% based on the weight of the diesters being condensed, the elevated temperature employed during the earlier part of the condensation to form the interpolyester is from about C. to about 220 C. and the low pressure defined under (F) is less than about 15 mm. of Hg pressure.

18. A linear interpolyester having a softening temperature differential of from about 5 to 20 C. consisting of a ratio of about 10 of one of the following repeating units:

to each 1 to about 30 of one of the following repeating units:

wherein s and 1 each represents a positive integer of from 1 to 4 and p represents a positive integer of from 2 to 12, which interpolyester has a low modulus of elasticity and is capable of being readily formed into shaped objects within its softening range, and wherein the -(CH2)p-- units in the molecular structure include a substantial proportion of such units wherein p is at least 4.

19. A linear interpolyester as defined in claim 18 wherein at least one of the repeating units depicted therein is replaced by a member selected from the group consisting of the following repeating units corresponding thereto:

wherein s and t each represents a positive integer of from 2 to 18, R7 represents an alkylene radical containing from 2 to 4 carbon atoms and q represents a positive integer of from 1 to 10.

12 20. A linear interpolyester as defined in claim 18 wherein p is 4, s is 1 and t is 1.

21. A linear interpolyester as defined in claim 18 whereinpis5,sis1andtis 1.

22. A linear interpolyester as defined in claim 18 whereinpis2,sis3 andtis3.

23. A linear interpolyester as defined in claim 18 whereinpis6,sis l and tis 1.

24. A linear interpolyester as defined in claim 18 wherein p is 8, s is 1 and t is 3.

References Cited in the file of this patent UNITED STATES PATENTS 2,437,046 Rothrock et al Mar. 2, 1948 2,465,319 Whinfield et a1 Mar. 22, 1949 2,547,113 Drewitt et a1 Apr. 3, 1951 2,623,033 Synder Dec. 23, 1952 FOREIGN PATENTS 621,997 Great Britain Apr. 25, 1949 

1. A PROCESS FOR PREPARING A LINEAR POLYESTER COMPRISING (A) CONDENSING ABOUT 10 MOLE PREPARATIONS OF A P,P''-SULFONYL DIBENZOIC DIESTER HAVING THE FORMULA: 